An Ordered Ni₆ -Ring Superstructure Enables a Highly Stable Sodium Oxide Cathode.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Sodium-based layered oxides are promising cathode materials for sodium-ion batteries (SIBs) due to their high capacity and conductivity.
• Performance limitations include phase transitions and air degradation, hindering practical application in grid energy storage.

Purpose of the Study:

• To mitigate performance issues in layered oxide cathodes by introducing an ordered Ni6-ring superstructure.
• To enhance the stability and electrochemical properties of sodium-ion battery cathodes through targeted ion substitution.

Main Methods:

• Synthesized a model compound, NaNi2/3Sb1/3O2, by substituting 1/3 of nickel with antimony in NaNiO2.
• Investigated the structural and electrochemical properties of the resulting material, focusing on the Ni6-ring superstructure.

Main Results:

• The ordered Ni6-ring superstructure significantly enhances air and thermal stability of the layered oxide cathode.
• Substitution improved redox potential and simplified the phase transition process during battery cycling.
• The symmetric atomic configuration and degenerate electronic orbitals contribute to improved material performance.

Conclusions:

• The ordered Ni6-ring superstructure is a key factor in developing highly stable layered cathodes for sodium-ion batteries.
• This study presents a new paradigm for designing advanced layered materials for energy storage applications.